The invention relates to a detecting and controlling appliance to be used with wave-emitting image-reproducing apparatus which can be used for switching an intermission light and controlling curtains or the like between performances of the image-reproducing apparatus. The appliance responds to the radiation, which may for example be light, ultrasonics or the like.
Conventionally the intermission light, the curtain or the like may be switched on or off, for example steplessly, by an operator. It is also known for narrow-gauge-film projectors to be provided with an intermission-light lamp on the apparatus itself, the lamp being controlled by the mode-selection switch of the apparatus. This avoids the need for a separate operator. The difficulty, however, is that such apparatus must be constructed in accordance with the different safety regulations for electrical apparatus which are in force in different countries. It is clear that this presents problems for mass-production of such equipment. The use of markings on the film for triggering control functions is also known, but this is impraticable with unmarked films and with television apparatus.